Poly alpha monoolefins stabilized with alkylated trisphenolic ether



Unite rates atent 31492829 PGLY ALPHA MGNQOLEFXNS STABTLEZEB vil'l'ilALKYLATED TREPHENQLTQ Belos E. llown, Baytown, Texx, assigner, by mesneassignments, to E550 Research and Engineering Company, Elizabeth,N..l'., a corporation or" No Drawing. Filed Apr. 4, 1961, Ser. No.M50549 (Jlairns. (Cl. 2.6fi45.5)

The present invention is directed to a polyolefin composition. Moreparticularly, the invention is concerned with a composition includingpolyolefins which are stable against heat and color degradation. In itsmore specific aspects, the invention is concerned with a composition ofpolyolefin, such as polypropylene, which does not deteriorate inmolecular weight or exhibit discoloration.

The present invention may be briefly described as a compound illustratedby the structural formula:

Where R and R are alkyl radicals containing 1 to 12 carbon atoms, and acomposition containing the compound and a costabilizer, such asdilaurylthiodipropionate, dicetyl sulfide,bis(tetradecylmercapto)-p-xylylene, or bis-(octadecylmercapto)-p-xylylene, in minor amounts and a major amount of apolyolefin, such as polypropylene. A compound Which has givensatisfactory results in polypropylene is 02 a-bis(3-t-butyl-5-methyl-2-hydroxyphenyl)-mesityl methyl ether.

In the practice of the present invention, the compound may be employedin an amount in the nnge from about 0.05 to about 1 percent by Weight ofthe solid polymer. An amount in the range from about 0.2 to about 05weight percent may be preferred.

The costabilizer may also be employed in an amount in the range fromabout 0.1 to about 1 percent by Weight of the solid polymer With anamount in the range from about 0.2 to about 5 percent by Weightpreferred.

It has been found that certain polyolefin polymers, when exposed tooxygen and/ or heat, will degrade and deteriorate, forming a color andlosing molecular Weight. In accordance With the present invention, thecompound mentioned before with the costabilizer serves to prevent colorloss and deterioration by loss of molecular Weight due to exposure tooxidative conditions.

The polyolefin polymers in accordance with the present invention arepolymers of olefins having 2 to 8 carbon atoms in the molecule and maysuitably be exemplified by polyethylene, polypropylene,ethylene-propylene copolymers, ethylene-butene-1 copolymers,ethylene-pentene-l copolymers, and the like, having molecular Weights inthe range from about 10,080 to about 1,000,000. These polymers areproduced by polymerization of the corresponding olefins employing theZiegler type polymerization catalyst which is obtained by at leastpartially reducing in solution in a diluent a halide of an amphotericmetal selected from groups TVB, VB, VB, and VIII of the periodic systemof elements (see, for example, the Henry D. Hubbard Periodic Chart ofthe Elements,

1947 ed, revised by W. F. Meegers; W. M. Welch Mfg. Co., Chicago, 111.).Examples of suitable halides from which the catalyst is prepared are thehalides of titanium, zirconium, hafnium, thorium, uranium, vanadium,columbiurn, tantalum, chromium, molybdenum, tungsten, and mixturesthereof. Exemplary of suitable compounds include titanium tetrachloride,titanium tetrabromide, zirconium tetrachloride, and the like.

in preparing catalysts suitable for use in forming the polymer treatedin accordance with the present invention, the amphoteric metal halide isreduced in solution in a nonreactive, nonpolar organic diluent in anysuitable manner, such as by means of chemical reaction with a suitablechemical compound having reducing properties, by irradiation, etc. Thisis done to reduce at least a portion, and preferably more than aboutpercent of the amphoteric metal halide, to a lower valence state. Theproduct of the reduction step, comprising the diluent and the at leastpartially reduced amphoteric metal halide, is employed as the medium inwhich olefin polymer zation is eilected.

The diluent to be employed should be a nonreactive, nonpolar organicmedium in which the amphoteric metal halide starting material is solubleto an extent at least suiiicient to provide an 0.1 Weight percentsolution of amphoteric metal halide starting material. Thus, forexample, in preparing the polymerization medium, an 9.1 to 10 Weightpercent solution of amphoteric metal halide in the diluent may beemployed.

Among the diluents that may be employed are saturated aliphatichydrocarbons, preferably containing from about 5 to 10 carbon atoms permolecule. Specific examples of such diluents include pentane, hexane,heptane, octane, decane, nonane, and mixtures thereof, or othersaturated petroleum hydrocarbons. A particularly desirable diluent isn-heptane. It will be understood that other hydrocarbon diluents may beused, such as aromatic diluents (benzene, xylene, etc), halogenatedaromatic hydrocarbons (monochlorobenzeue, dichlorobenzene, etc.) gas oildistillate fractions obtained from the catalytic cracking of virgin gasoil feed stocks, diesel oil, etc. t Will be understood that, if desired,mixtures of two or more compatible, miscible diluents may be employed.The diluent should be substantially completely free from oxygen, Waterand similar compounds of strong polarity which are reactive with theproducts obtained by reduction of the amphoteric metal halide.

The nonpolar organic liquid in Which the slurry is formed may suitablybe identical with the diluent in which the catalyst is formed forpolymerizing the olefinic compounds.

The polymerization reaction is suitably conducted at a temperature inthe range from about to about 460 F., preferably at about roomtemperature. Higher temperatures may be employed, but are generallyundesirable in that catalyst decomposition may be encountered.Subatmospheric pressures and pressures up to about 250 atmospheres maybe employed in forming the polymer treated in accordance with thepresent invention. it is generally preferable to employ in thepolymerization technique a comparatively low pressure, and specificallyit is desirable to employ atmospheric pressure. Reaction times of about60 minutes are required, although reaction time may vary Within therange of about 10 minutes .to about 24 hours.

success As a result of subjecting the olefins of the type illustratedbefore to treatment with a catmyst of the nature described, olefinpolymers are formed having the moleculm weights recited which areessentially insoluble in the nonpolar organic liquid and form a slurryof polymerized olefins in the non-polar organic liquid. It is thesepolymers, after quenching to deactivate any catalyst and separation fromthe slurry, which are treated by adding the stable additives, inaccordance with the present invention, since the polymer particles arein a finely divided state, have a high surface area, and rapidly adsorboxygen.

in adding the m a -b=iS (3-t-butyl-5-methyl-2-hydroxyphenyl) mesi-tylalkyl ether and the costabilizer to the polyolefin of the presentinvention, the additives may suitably be employed and incorporated inthe po lyolefin by forming a solution of the particular additives in asuitable solvent such as an aromatic hydrocarbon. The ether compound maysuitably be added in any suitable solvent such as methanol, xylene,hexane, etc. while the costabilizer may suitably be employed in anysuitable solvent such as methanol, xylene, hexane, etc. The twoadditives may be sprayed over the pellets or particles of polymers andthe resulting mixture may then be extruded through a suitable extrusiondevice to cause the formation of a homogeneous mixture. While it ispreferred to add the two additives to the polyolefin in a solution, theysuitably may be added as such to the polymer particles and the resultingmixture subjected to milling or extrustion as desired to cause intimateadmixture of the additives with the polymer composition to form ahomogeneous mixture.

The composition of the present invention is quite important and usefulin formation of products such as molded and extruded devices andarticles, or the composition may be formed in films for use in wrappingfoodstuffs and other articles, or the polymer composition may beextruded as a filament to be used in weaving and forming of cloths,fibers, and other similar materials.

In order to illustrate the invention further, reference is had to Tablel, where compositions of polypropylene and the several components of thecomposition were made up. These compositions were submitted to thermaland oxidative conditions to determine the stabilizing effect of thevarious additives.

TABLE 1 Thermal an d Oxidative Stability of Polypropylene With VariousStabilizing Systems Sample Wt. Color of Oxidative N 0. Stabilizer systempercent polymer pad stability,

days a Compound I 0.2 brown 4 Compound II 0. 2 white 2% DLTDP Compound0. 3, 0. 1 light brown. 20

DIL TDP, Compound 0.3,0. 1 white 25 DL' lDP, Compound 0. 5, 0.1 lightbrown." 34

I. DfiTLP, Compound 0. 5, 0. 1 white 48 Dicetyl Sulfide, 0. s, 0. 1 do20 Compound II. Bis(tetradecylmer- 0. 3, 0.1 -do 20 capto)p-xylylene,Compound 11.

a 150 C., 4 co. air/min. b Dilaurylthiodipropionate.

In the foregoing table, compound I is the compound represented by thefollowing structural formula:

A while compound II is 0: or -bis(3-t-butyl-5-methyl-2-hydroxyphenyl)-mesityl methyl ether of the present invention.

It will be apparent from the data in Table I that neither compound I norcompound II alone in polypropylene is satisfactory as to oxidativestability although compound ll does not discolor a pad or sample of thepolypropylene. Compound I in combination with the costabilizer,dilaurylthiodipropionate, does not confer as great an oxidativestability to the composition as does compound ll with thedilaurylthiodipropionate. it is to be especially noted that thecompositions of the present invention not only are stable but also arenot affected detrimentally by developing an undesirable browncoloration. it is also noteworthy that larger amounts of compound llincreased the oxidative stability to a greater extent than the sameamount of compound I. Finally, it is to be noted that severalcostaoilizers have been found to be elfective; and these are only by wayof illustration, and not limitation, since there exists a large numberof such costabilizers which would also be efective.

The compounds or" the present invention may suitably be prepared byreacting a compound such as:

in the form of its sodium salt with an alkyl sulfate such as dimethylsulfate in solution in a suitable solvent such as toluene to obtain areaction product which precipitates from the reaction medium and may berecovered by filtration of the mixture followed by washing withpetroleum ether and recrystallization as may be desired.

For example, a -bis(3-t-butyl-5-methyl-2-hydr0xyphenyl)-mesitol,compound I, is prepared as follows:

2,6-dimethylOI- t-methylphenol is prepared according to the method ofBeaver et al. (see D. J. Beaver, R. S. Shumard, and P. l. Stoliel,Journal American Chemical Society, vol. 75, p. 5579, 1953);

Then, 98.4 g. (0.6 mole) 2-t-butyl-4 methylphenol is placed in a flaskequipped for stirring, a condenser, a trap for removing condensed water,and a nitrogen blanket. The flash is worked sufiicient to liquefy thephenol;

Then, while stirring vigorously 16.8 g. (0.1 mole) of the2,6-dimethylol-4-methylphenol is added in one portion followed by 4 ml.of concentrated HCl. The mixture is then heated to C. md held for 36hours while the water of the reaction is gradually removed. The mixtureis cooled to room temperature; 100 ml. of n-heptane is added and themixture allowed to stand. Colorless crystals come down and these arefiltered, washed with petroleum ether, and dried. There is obtained 9.7g. (21% yield) of compound I, M.P. l74l75 C.

The 11 ct -blS(3-t-btliyl 5 methyl-Z-hydroxyphenyl)- mesityl methylether, compound II, is then prepared as follows:

6.9 g. (0.015 mole) of the compound I (MP. 174- 175 C.) is dissolved in50 ml. of dry toluene and placed in a dash equipped for stirring, acondenser, and an inert gas blanket. Then 0.35 g. (0.015 mole) of sodiumis added and the mixture heated until the sodium has reacted. 2 g. ofdimethyl sulfate in 10 ml. toluene is added dropwise. A whiteprecipitate appears; it is filtered and Washed repeatedly with petroleumether and then dried. There is obtained 2.8 g. (40% yield) of compoundll, Ml. 202-203 C.

The nature and objects of the present invention having been completelydescribed and illustrated, what we wish 2. A composition in accordancewith claim 2 containing dilaurylthiodipropionate as a costabilizer.

3. A composition in accordance with claim 1 in which the solid polymeris polypropylene.

6 4. A composition in accordance with claim 1 in which the amount of thecompound and the dilaurylthiodipropionate each is within the range fromabout 0.05 to 1.0% by Weight of said composition.

5. The compound:

v CH3 JHa (B113 References Cited in the file of this patent FOREIGNPATENTS 208,596 Australia Oct. 27, 1955 845,608 Great Britain Aug. 24,1960

1. A COMPOSITION CONTAINING A SOLID POLYMER OF AN ALPHA MONOOLEFINHAVING 2 TO 8 CARBON ATOMS IN THE MOLECULE AND A MOLECULAR WEIGHT IN THERANGE FROM ABOUT 10,000 TO ABOUT 1,000,000 AND A STABILIZING AMOUNT OFTHE COMPOUND: